Drainage screen



June 22, 1937. L. w. WA 'ISON ET AL 2,084,753

DRAINAGE SCREEN Filed Aug. 20, 1935 FIE ZL I II I I I O 1! Ill:

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Patented June 22, 1937 UNITED STATES PATENT OFFICE DRAINAGE SCREEN Lloyd W. Watson,

Ackcrly, Jr., Oliver United Filters Oakland, and Orville B. Piedmont,

Calif., assignors to Incorporated, San Fran- 4 Claims.

This invention relates in general to filters and in particular to a drainage member for filters.

In general, the object of the invention is the provision of a drainage screen or member for filters which will give an unrestricted passage to the flow of liquid therethrough, and which can be economically manufactured.

The invention possesses other advantageous features, some of which with the foregoing, will be set forth at length in the following description where that form of the invention which has been selected for illustration in the drawing accompanying and forming a part of the present specification is outlined in full. -In said drawing, one form of the invention is shown, but it is to be understood that it is not limited to such form, since the invention as set forth in the claims may be embodied in a plurality of forms.

Referring to the drawing: l

Figure 1 is a top plan view of a sheet of rolled expanded metal provided with spaced parallel ribs pressed into its surface.

Figure 2 is a section taken on the line 2-2 of Figure 1.

Figure 3 is a partial section taken through a drainage member formed by a pair of superposed sheets, such as shown in Figures 1 and 2.

Figure4 is a sectional detail of a leaf filter, the drainage member of which is formed by a pair of superposed expanded metal sheets as shown in Figure 3.

Our invention contemplates the use of a sheet of expanded metal which as is well known to the trade, is formed by slitting a sheet of metal and then expanding the sheet thus slit so as to form an open-work or mesh structure. The bars defining the opening in a structure of this kind, are inclined to the general plane in which the sheet lies, and therefore it is rolled so as to make the plane of the bars lie in the general plane of the sheet.

As shown in each of the four figures of the drawing, a sheet I of this character is provided with a plurality of spaced parallel interrupted ribs 2, by means of a. pressing or stamping opera-' tion. These ribs are preferably stamped in line with the apices of the diamond shaped meshes of which the sheet I is formed, and it will be noted that the stamping operation forms valleys or channels 3 opposite the ribs 2 and in line therewith. As shown in Figures 3 and 4 a drainage member for filters may be readily formed by superposing two sheets as constructed in the above manner and held in spaced relation with each other, by means of the interrupted ribs 2. The

ribs of one sheet are preferably disposed intermediate the ribs of the other sheet, so as to form a symmetrical structure through which uniform drainage can take place.

As shown in Figure 4 the peripheral edges 4 of the sheet I are brought together and secured to a peripheral frame member 5, by means of rivets 6. The drainage member so formed is covered by means of a filter medium I which is secured to the frame 5 by means of a T bar 8 the leg of which is accommodated in a channel 9 formed in the frame 5.

From a study of Figure 1 it will be noted that the ribs 2 are not continuous, but are interrupted by the meshes or openings H of the sheet, and

that as a consequence the filtrate passing through the filter medium I is free to flow by the shortest path to the filtrate outlet nipple of the filter leaf (not shown) regardless of where such outlet may be located. Another very important advantage of a drainage member of this kind is that its outer faces are smooth, and therefore the wear of the filter medium in contact with it is far less than the wear of a filter medium in line contact with a wire mesh drainage member, such as has been customarily used for many years. A third and equally important feature of a drainage member of this kind is that its cost of manufacture is far less than any other type of drainage member of which we have any knowledge. It should be further noted that the ribs 2 not only serve as spacing members, but also reinforce the structure to a considerable extent.

We claim:

1. A drainage member for filters comprising a pair of superposed reticulated metal sheets held in spaced relation with each other by means of spaced parallel rows of interrupted ribs pressed into the inner face of each of said sheets.

2. A drainage member for filters comprising a pair/of superposed sheets of rolled, expanded metal held in spaced relation with each other by means of spaced parallel ribs formed on the inner face of each of said sheets.

3. A drainage member for filters comprising a pair of superposed reticulated metal sheets held in spaced relation with each other by means of parallel ribs pressed into said sheets at spaced intervals.

4. A drainage member for filters comprising a pair of superposed, reticulated metal sheets held in spaced relation with each other by means of spaced parallel ribs pressed into said sheets and secured at their edges to a frame member.

LLOYD W. WATSON. ORVILLE B. ACKERLY, JR. 

